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    User name brads

    Log entry time 00:03:02 on April 06, 2008

    Entry number 230220

    Followups:

    keyword=To all analysis code people -- we have no quad-core machines

    Here are the number of cpu's on each of the adaq analysis machines:
    
      adaql3:  2 cores
      adaql4:  1 core
      adaql5:  2 cores
      adaql6:  1 core
      adaql7:  1 core
    
    Yes I know 'top' shows twice as many.  That is due to Intel's
    "Hyperthreading"
    feature being enabled.  Hyperthreading is a questionable feature created by
    Intel whereby the CPU and motherboard can be made to lie to the OS about how
    many cores reside in a given chip.
    
    It doesn't actually improve things in real life except in a few corner cases.
    Cache misses and other scheduling details usually mean running 2 jobs on a
    pretend-dual core CPU takes _longer_ than running those two jobs
    sequentially.
    And, more to the point, slows the machine to crawl making it a pain for
    others
    to work on.
    
    So, please run at most 1 analysis job per physical core.  Life will be
    better.
    
    You may now return to analyzing code.
    


    A copy of this log entry has been emailed to: xqian@jlab.org,jinhuang@jlab.org,moffit@jlab.org